The invention relates to a method and apparatus for making article shapes from composite materials where one of the materials consist of longitudinally extending strands in a matrix with another material which has been solidified from a liquid state.
Heretofore, various methods have been utilized for producing fiber or laminae reinforced metal-metal, ceramic-metal, plastic-ceramic, and other composite articles. Some of the methods more commonly used are the method of directional solidification of eutectic alloys, the liquid phase infiltration method, and the process of passing fibers through a molten bath of a metal matrix and bonding the fiber and matrix adhered thereto in closed dies. However, none of the above methods provide an opportunity to produce fiber or laminae reinforced shapes of complicated configurations with a predetermined distribution of the fibers in the transverse section of the shapes to provide desired reinforcing or structural properties.
The method of directional solidification of eutectics provides a one-step production of composite materials, however, this method is confined to a very limited group of eutectic systems and serves to obtain ingots with strictly determined characteristics of distribution of phases and properties during solidification (see Thomson and Lemkey, "Composite Materials", Vol. 4, Academic Press, New York, 1974). Apparatus for carrying out this method typically includes a mold which is placed in a furnace and heated until the metal becomes molten and is thereafter withdrawn and cooled according to known techniques.
In the method of liquid phase infiltration, the metal is moved by pressure or vacuum into a volume with strands of fibers. The apparatus consists of a mold packed by strands of fibers which form a natural net of capillaries. The mold is connected with a volume of liquid metal which is forced by pressure or vacuum through these capillaries. The method can be used for articles of simple shapes (ingots, rods) and very limited length because of difficulties with creating pressures high enough to move the metal through long capillaries. This method cannot be used for metals and fibers which have an ability of chemical interaction.
Another method of drawing fibers through a molten bath includes the agitation of the interfaces of the fibers and the matrix in the molten bath in the contact zone and cannot be used with material with significant chemical interaction. This method has been utilized mainly to produce rods or sheets with uniformity of properties in their transverse sections. The apparatus for carrying out the method typically includes a molten metal bath through which metal fibers are drawn. The metal is cooled and adheres to the fibers which are pulled therethrough whereafter the solid composite is pulled through a die which shapes the metal matrix around the fibers.
It has also been known to pull a molten metal through a shape plate having a desired shaped opening and thereafter cooling the molten metal to produce a solidified shape. However, this method produces only a plain article of the desired shape and does not provide for the production of composite articles from two or more materials.
Accordingly, an important object of the present invention is to provide a method and apparatus for producing shapes from composite materials in a one-step process in which the distribution of mechanical and physical properties in the composite articles may be predetermined by selectively arranging reinforcing fibers or laminae in the article.
Still another important object of the present invention is to provide a method and apparatus for producing reinforced composite article shapes from two materials in a liquid state.
Still another important object of the present invention is to produce composite article shapes with minimal interfacial reaction in composites by utilizing solid fibers and a liquid matrix material .
Yet another important object of the present invention is to provide a method and apparatus for producing article shapes from composite materials where there is no relative movement between a fiber material and a matrix material in the contact zone by pulling the composite materials together through a shaped plate.